PURPOSE: To facilitate the detection of speed, by forming a magnet for magnetic levitation on the circumferential section of a rotating armature and stationary field magnets confronted with each other, to levitate and rotate a rotor, and by detecting the output of the conductive pattern of the circumferential section of a stator.

CONSTITUTION: On a rotary shaft 5 retained rotatably by bearings 3, 4, an armature 6 consisting of a plurality of armature coils 7 is fitted. The coils 7 are excited via a commutator 8 and a brush 11. On the outer peripheral section of the armature 6, a magnetically levitated magnetic pole 13 is formed with a plastic magnet 12. A stator is formed with a plastic ring 10 and a plurality of field magnets 9, and also on the outer peripheral section of the stator, a magnet 16 for magnetic levitation is formed and is confronted with the magnetically levitated magnet 13, and a printed board 19 between them is provided with a conductive pattern 20. The armature 6 is levitated and rotated to obtain output from terminals 20b, 20c and to detect the speed. As a result, an economical miniature speed detection mechanism can be formed.